The invention relates to power tools and, more particularly, to a method for assembling and an electrical connector assembly for a power tool.
A typical power tool includes a motor housing and an electric motor supportable by the motor housing and electrically connectable with a power source. The electric motor may include a field assembly, including one or more field windings, a rotatable armature supporting a commutator, a carbon brush for electrically engaging the commutator, and a switch for electrically connecting the components of the electric motor to the power source. In some power tools, the components of the electric motor are directly electrically wired to one another to provide a complete electrical circuit for the motor.
In some other power tools, the components of the electric motor include respective terminals and the motor also includes an electrical connection system electrically connecting the motor components. In such power tools, the electrical connection system includes separate contact strips which are separately mounted on the housing. Once mounted, the forward ends of the contact strips are engaged with the field terminals, and the rearward ends of the contact strips engage the brush terminals or the wiring harness for connection to the switch to provide a complete electrical circuit for the motor.
One problem with power tools having above-described directly-wired components is that direct wiring of the motor components during assembly of such power tools is time-consuming and labor-intensive, greatly increasing the cost and the complexity of the method and the machinery for assembling the power tools.
One problem with the power tool with the above-described electrical connection system including contact strips is that, while the contact strips improve the efficiency of assembly of the power tool, each of the separate contact strips must be accurately positioned and fixed to the housing so that the components of the motor can be electrically connected. If a contact strip is improperly positioned or improperly fixed to the housing, corrective action is required so that the motor components can be electrically connected to one another, reducing the efficiency of the assembly process.
Another problem with the power tool with the above-described electrical connection system is that the motor housing must be designed to fixably support and retain the contact strips in the required position. If the motor housing is improperly formed, the motor housing will not support the contact strips in the required location (for proper connection to the motor components) and, therefore, will not be useable.
Yet another problem with the above-described power tools is that, because the direct wires or the contact strips do not provide additional structural rigidity to the motor housing, the motor housing, which is typically formed of a moldable material, requires a greater amount of material and a more durable material, increasing the cost of the power tool.
Another problem with some of the above-described power tools is that the power tool cannot be configured to have different operating conditions, such as with or without a braking capability, without changing the wiring or the electrical connection system of the power tool.
The present invention provides a method for assembling and an electrical connector assembly for a power tool that alleviates the problems with the above-described power tools. In some aspects, the invention provides a one-piece trace or spider terminal member assembly which provides points of connection for the motor components, such as the field assembly, the brushes and the switch. To assemble the motor, the one-piece terminal member assembly is positioned in the motor housing. To mount the terminal member assembly, the terminal member assembly is preferably co-molded as a unit with the housing or, alternatively, may snap-fit into connectors formed on the housing. The terminal member assembly and the housing are then preferably punched or stamped at points to provide the necessary number of electrically separated contact elements to connect the components of the motor. For example, the female ends or terminals of the field assembly, the brushes and the switch are connected to the electrically separated contact elements to provide a suitable complete electrical circuit for the motor. A non-conducting plug may fill the openings created by punching or stamping. The plug also confirms that the openings were punched or stamped. Further, the plug provides a seal to prevent debris from entering the opening and effecting the electrical circuit of the motor. More particularly, the invention provides a method for assembling a power tool, the power tool including a motor housing, and a motor supportable by the housing, the method comprising the acts of providing a terminal member assembly including a plurality of electrically separable contact elements, mounting the terminal member in the motor housing, electrically separating the plurality of electrically separable contact elements of the terminal member assembly from one another to provide a corresponding plurality of electrically separated contact elements, supporting the motor in the motor housing, and electrically connecting the plurality of electrically separated contact elements to the motor to provide a complete electrical circuit for the motor.
Preferably, the housing is formed of a molded material and the act of mounting the terminal member assembly includes molding the terminal member assembly as a unit with the motor housing. Also, the act of separating preferably includes creating an opening in the terminal member assembly between adjacent ones of the plurality of electrically separable contact elements to provide the plurality of electrically separated contact elements.
In addition, the act of creating an opening may preferably include punching an opening in the terminal member assembly between adjacent ones of the plurality of electrically separable contact elements to provide the plurality of electrically separated contact elements. Preferably, the act of punching provides a corresponding hole in the motor housing substantially aligned with the opening between adjacent ones of the plurality of electrically separated contact elements.
The method may further preferably comprise the act of positioning a non-conducting element in the opening between adjacent ones of the plurality of electrically separated contact elements and, preferably, through the corresponding hole in the motor housing. Also, the method may further preferably comprise the act of providing a separate motor housing cover having the non-conducting element mounted thereon, positioning the separate motor housing cover over the motor housing, and positioning the non-conducting element in the opening between adjacent ones of the plurality of electrically separated contact elements.
The motor may include a field having a plurality of field terminals, and each of the plurality of electrically separated contact elements may have at least a first contact. Preferably, the act of supporting the motor includes supporting the field in the motor housing, and the act of electrically connecting the plurality of electrically separated contact elements to the motor includes electrically connecting the first contact of a corresponding one of the plurality of electrically separated contact elements with one of the plurality of field terminals. Preferably, the act of supporting the field occurs substantially simultaneously with the act of electrically connecting the first contact of the corresponding one of the plurality of electrically separated contact elements with the one of the plurality of field terminals.
Also, the motor may include a switch having a switch terminal, and at least one of the plurality of electrically separated contact elements may have a first contact and a second contact. Preferably, the act of supporting the motor includes supporting the switch on the motor housing, and the act of electrically connecting the plurality of electrically separated contact elements to the motor preferably includes electrically connecting the switch terminal to the second contact of the at least one of the plurality of electrically separated contact elements. The act of supporting the switch may occur substantially simultaneously with the act of electrically connecting the switch terminal to the second contact of the at least one of the plurality of electrically separated contact elements.
The motor may further include a braking circuit and switch assembly having a braking circuit electrically connected to a switch and a plurality of assembly terminals, and at least another one of the plurality of electrically separated contact elements may have a first contact, a second contact and a third contact. Preferably, the act of supporting the motor includes supporting the braking circuit and switch assembly on the motor housing, and the act of electrically connecting the plurality of electrically separated contact elements to the motor includes electrically connecting one of the plurality of assembly terminals to the second contact of the at least one of the plurality of electrically separated contact elements and electrically connecting another of the plurality of assembly terminals to the third contact of the at least another one of the plurality of electrically separated contact elements.
In addition, the motor may include a brush having a brush terminal, and at least one of the plurality of electrically separated contact elements may have a first contact and a second contact. Preferably, the act of supporting the motor includes supporting the brush on the motor housing, and the act of electrically connecting the plurality of electrically separated contact elements to the motor includes electrically connecting the brush terminal to the second contact of the at least one of the plurality of electrically separated contact elements. Preferably, the act of supporting the brush occurs substantially simultaneously with the act of electrically connecting the brush terminal to the second contact of the at least one of the plurality of electrically separated contact elements.
The invention also provides a power tool comprising a motor housing, an electric motor supportable by the motor housing and electrically connectable with a power source, and an electrical circuit assembly. The electrical circuit assembly is provided by a method comprising the acts of providing a terminal member assembly including a plurality of separable contact elements, mounting the terminal member assembly to the motor housing, separating at least two of the plurality of separable contact elements of the terminal member assembly to provide a corresponding plurality of electrically separated contact elements, and electrically connecting the plurality of electrically separated contact elements to the motor to provide a complete electrical circuit for the motor.
The invention additionally provides an electrical connector assembly for a power tool, the electrical connector assembly provided by a method comprising the acts of providing a terminal member assembly including a plurality of electrically separable contact elements, mounting the terminal member assembly to the motor housing, electrically separating the plurality of electrically separable contact elements of the terminal member assembly to provide at least a first electrically separated contact element and a second electrically separated contact element, and electrically connecting the first electrically separated contact element and the second electrically separated contact element to the motor to provide a complete electrical circuit for the motor.
The invention further provides an assembly for use in manufacturing a power tool, the assembly comprising, a motor housing for supporting the motor of the power tool, and an electrical connector assembly. The electrical connector assembly is provided by a method comprising the acts of providing a terminal member assembly including a plurality of separable contact elements, mounting the terminal member assembly to the motor housing, and separating the terminal member assembly to provide at least a first electrically separated contact element and a second electrically separated contact element, the first electrically separated contact element and the second electrically separated contact element being electrically connectable to the motor to provide a complete electrical circuit for the motor.
The invention also provides a method for assembling a power tool comprising the acts of providing a motor and a terminal member for connecting the motor to a power source, forming a motor housing of a moldable material, the act of forming including molding the terminal member with the moldable material of the motor housing, supporting the motor in the housing, and electrically connecting the terminal member and the motor to provide a complete electrical circuit for the motor.
The invention additionally provides a method for assembling a power tool comprising the acts of providing a first electrical component and a second electrical component, providing a terminal member for electrically connecting the first electrical component to the second electrical component, the terminal member including a plurality of separable contact elements, forming a power tool housing of a moldable material, the act of forming including molding the terminal member with the moldable material of the housing, separating the terminal member to provide a corresponding plurality of electrically separated contact elements, supporting the first electrical component and the second electrical component on the housing, and electrically connecting the plurality of electrically separated contact elements to the first electrical component and to the second electrical component to provide a complete portion of the electrical circuit for the power tool.
One advantage of the present invention is that, with the method for assembling and ala the electrical connector assembly of the present invention, assembly of a power tool is less time consuming and less labor-intensive. The motor components are more easily electrically connected to one another with the terminal member assembly, reducing the cost and the complexity of the method and machinery required to assemble a power tool.
Another advantage of the present invention is that, because, in some constructions, the plurality separable contact elements is mounted to the housing as a unitary terminal member assembly, the plurality of electrically separated contact elements is more accurately positioned and supported in the housing, also reducing the cost and complexity of the method and the machinery required to assemble a power tool.
A further advantage of the present invention is that, when the terminal member assembly is molded with the housing, the housing does not have to be specially designed to fixably support and retain the terminal member assembly in the required position.
Yet another advantage of the present invention is that, when the terminal member assembly is molded with the housing, the terminal member assembly and the plurality of electrically separated contact elements provide additional rigidity and strength to the housing. As a result, less material or less durable material may be used to form the housing while maintaining the strength of the housing.
Another advantage of the present invention is that, in some constructions, the terminal member assembly can accommodate different motor components so that the power tool can be configured to provide different operating conditions. For example, in some constructions, the power tool with such a terminal member assembly can alternately include an on/off switch assembly or a braking circuit and on/off switch assembly without requiring a change to the terminal member assembly.